Study explores capture of clean carbon dioxide from landfill gases

Delta greenhouse already generates heat, electricity from waste

A Village Farms employee at the company’s Ladner greenhouse, which burns methane gas from the Vancouver landfill to generate heat and electricity.
Photograph by: Arlen Redekop , Vancouver Sun

Local greenhouse grower Village Farms is hoping to extract clean carbon dioxide — as well as heat and electricity — from the landfill gases it burns.

The Delta-based grower has been burning methane gas from Vancouver’s landfill to generate heat and electricity for 12 years at the firm’s Ladner facility under an agreement with the City of Vancouver and BC Hydro, according to the firm’s development director Jonathan Bos. But because landfill gas is chemically inconsistent and contains contaminants, the CO2 generated by the process isn’t clean enough to be used in greenhouses and is released in exhaust.

Cogeneration using natural gas is widely regarded as a clean source of carbon dioxide and energy, said Bos. “But landfill gas is a completely different animal.”

Bos hopes a new $300,000 feasibility study — by Hallbar Consulting and the Swedish Institute of Agricultural and Environmental Engineering and funded by the Innovation Agriculture Foundation of B.C. and several industry partners — will change that, helping end the waste of a rich but untapped source of CO2.

“Landfill gas is more than 50 per cent CO2 before we burn it, so it really is a wasted resource,” said Bos.

A breakthrough that allows clean carbon dioxide to be recovered from landfill gas would be a double win, enabling the industry to extract maximum value from a waste-stream resource and potentially improving air quality in the Fraser Valley, where the greenhouse growers are concentrated.

“The people of Greater Vancouver and our own families are real stakeholders in this process,” said Bos. “We have the potential to make a long-term positive impact on emissions.”

British Columbia’s greenhouse growers are voracious consumers of carbon dioxide, a gas that is essential to plant growth and which can boost yields by up to 30 per cent when piped into greenhouses, according to a recently published government discussion paper. Greenhouses maintain CO2 levels of 800 parts per million or more, roughly double the amount that occurs in our atmosphere.

Most greenhouse growers in B.C. — including Village Farms — obtain carbon dioxide by burning natural gas, according to Linda Delli Santi, executive director of the B.C. Greenhouse Growers’ Association, a funding partner in the project.

Greenhouses use the heat created by the process to maintain optimal temperatures inside the greenhouses and a handful also generate electricity, which can be sold onto the power grid.

Landfill gas, which contains methane, can be recovered for use as a fuel or it must be flared to prevent it escaping into the atmosphere. Methane is extremely harmful to the ozone layer in earth’s upper atmosphere and is a potent greenhouse gas.

Flaring, however, releases carbon dioxide and, while it is less harmful than methane, it is also believed to fuel global warming.

“Landfill gas is an ugly, corrosive fuel and that creates all kinds of problems,” said Bos. “But there is an appetite for the CO2, a fuel source and an environmental benefit to finding a solution.”

The region’s greenhouses as well as funding partners such as Air Liquide and the B.C. Food and Beverage Association are potential customers for a clean, cheap source of carbon dioxide, Bos said.

“What we hope is to identify a process to collect (carbon dioxide) from landfill gas combustion that will be safe for people and safe for plants,” he said.

The consultants will spend the better part of the next year scouring the world for technologies and processes that can be adapted to the needs of the industry.